The technical field is packaged designs for mounting semiconductor devices.
Current packages for semiconductor devices, such as light emitting diodes (LED) may be xe2x80x9cthrough the holexe2x80x9d or surface mount types. These packages are used with printed circuit boards (PCBs) and may require a specialized assembly process to securely mount a semiconductor device into the PCB. A soldering process is then applied to electrically and thermally connect the semiconductor leads to the PCB. In the case of a LED, this PCB connection method allows an LED inside the package to be powered and lighted up.
Current LED packages have either flimsy leads (lead frame platform) or no leads (PCB platformxe2x80x94that utilizes plated gold or tin traces as conducting paths) for connecting to the PCB or hard wires. These current LED packages inherently offer very poor thermal spreading and conducting characteristics for removing heat generated by the LED chip inside the LED package. Hence, current LED packages seldom operate at power more than 0.3 watts.
Current LED packages also suffer from other defects including a large package footprint. Where flux per package per footprint area is a factor, for example illumination inside an instrument panel, current LED packages are difficult to apply. Also, existing LED packages may be too large to form close clusters of different color LEDs inside a reflective (mixing) chamber, to obtain specific spectral effects and luminous efficiency.
A concentrically leaded power semiconductor device package eliminates problems inherent in current semiconductor package designs. The package offers the possibility to avoid or minimize the use of soldering processes in the application assembly. The package also provides for superior heat dissipation. The package comprises a pair of coaxial round or square wire leads, which are electrically separated by a thin dielectric film. The package does not need to be mounted on a PCB to be powered up. Leads from the package may be securely mounted on a low cost connector, which may be designed to also function as a heat sink, by simply plugging the package into the connector. As the connector supplies power to the LED, the connector also removes heat generated by the LED. The package delivers excellent thermal spreading and conducting properties to LEDs packaged inside. This may be achieved by attaching the LED chips on the end face of a straight wire (inner) at one end and allowing an opposite end of the same wire to be inserted into the heat sink in an application assembly. Alternatively, an outer wire, or conductor, may be inserted into the heat sink. The wire diameter and material selection may be based on a thermal performance of the LED chip package. A thermal compound or grease may be used to reduce the thermal resistence at the interface between the cylindrical surfaces of the inner wire and the heat sink of the connector. This design scheme allows a high-power LED to be packaged and operated at high wattage without overheating.
In addition to a coaxial cylindrical or square design, the package may incorporate multiple layers of coaxial conductors. For example, the package may include three concentric cylindrical conductors. Such a design allows for the use of multiple LEDs. Other variations of the package configuration may incorporate LEDs and other devices, including semiconductor devices, resistors and capacitors, attached on a cutaway section of one of the semiconductors. This variation of the package design may be useful for a semiconductor laser, for example.